Fix #11787 – Improve scene height picking performance

[ggetz]

Description

• Pulls in some performance fixes from 3d tiles height reference #11604 (whichever gets merged first is fine)
• Don't pick the ground height each frame: Only when the camera moves or when additional data is loaded.
• Configure the powerplant tileset to skip camera collision as it is an "indoor tileset"

Issue number and link

Fixes #11787

Testing plan

Add the following line to any Sandcastle example to check the framerate:

viewer.scene.debugShowFramesPerSecond = true;

• Open and move around updated sandcastle examples, verifying thee frame rate is not impacted and that you can navigate inside the powerplant tileset
• Verify other 3D tiles examples, such the Google examples, and confirm frame rate isn't significantly impacted

Author checklist

• I have submitted a Contributor License Agreement
• I have added my name to CONTRIBUTORS.md
• [ ]I have updated CHANGES.md with a short summary of my change Not needed, the original feature has not yet been shipped
• I have added or updated unit tests to ensure consistent code coverage
• I have update the inline documentation, and included code examples where relevant
• I have performed a self-review of my code

[ggetz]

@jjspace can you please review?

[jjspace]

Updates look good and most of the Sandcastles run much smoother.

I did notice pretty bad framerate in the 3D Tiles Clipping Planes and MSAA Sandcastles still.

I just had one small question. Also please merge main 🙏

[ggetz]

Thanks @jjspace, this should be ready to go.